[duplicate-code] Duplicate Code Analysis Report

[github-actions]

Analysis of commit 9a493ea2826dbcc6b27a3f2780c95f37d317c0a7 — refactor: move DIFC filter events into JSONL log (#2077)

Summary

Analysis of the latest commit found 2 significant duplication patterns introduced in internal/server/difc_log.go. Both patterns are directly related to the new DIFC filter event logging code.

Detected Patterns

This analysis found 2 significant duplication patterns:

1. Near-Identical Struct Definitions with Verbatim Field Copy — Severity: Medium — See sub-issue [duplicate-code] Duplicate Code Pattern: FilteredItemLogEntry mirrors JSONLFilteredItem fields #2086
2. Duplicate tagsToStrings utility function — Severity: Low — See sub-issue [duplicate-code] Duplicate Code Pattern: tagsToStrings duplicates difc.TagsToStrings #2087

Overall Impact

• Total Duplicated Lines: ~35 lines
• Affected Files: 3 files (internal/server/difc_log.go, internal/logger/jsonl_logger.go, internal/difc/tags.go)
• Maintainability Risk: Medium — field additions to the DIFC filtered-item data shape require parallel edits in two structs
• Refactoring Priority: Medium — the struct duplication is actionable and low-risk to fix

Next Steps

1. Review individual pattern sub-issues for detailed analysis
2. Eliminate the redundant tagsToStrings in difc_log.go by using the existing difc.TagsToStrings
3. Consolidate FilteredItemLogEntry and JSONLFilteredItem to reduce parallel field maintenance

Analysis Metadata

• Analyzed Files: 75 Go source files changed in this commit (test files excluded)
• Detection Method: Semantic code analysis + grep-based pattern search
• Commit: 9a493ea2826dbcc6b27a3f2780c95f37d317c0a7
• Analysis Date: 2026-03-18